• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.3
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• pp.265-273
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• 2006

In the decommissioning and decontamination(D&D) planning stage, it is important that the scenarios are evaluated from an engineering point of views because the decommissioning work has to be executed economically and safely by following the best scenarios. Therefore, we need to develope several modules to evaluate the decommissioning scenarios. In this paper, the digital mock-up system is constructed in the virtual space to simulate the whole decommissioning process. The schedule evaluating equation and cost evaluation equation are derived to calculate the working time and the expected cost. And in order to easily identify the radiation level about the activated objects, the radiation visualization module is developed. Finally, on the basis of the obtained results from the Digital Mock-up and other important factors, the evaluating method of the scenarios that can indicate the best scenario is described.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.3
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• pp.237-247
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• 2005

It is necessary to forecast the various dismantling activities prior to dismantling nuclear facilities by using various software instead of a physical mock-up system because the dismantling in a contaminated with radioactivity cause the results of an unexpected situation. The component that needs to develop a dismantling mock-up system was examined. There are many component systems such as a decommissioning database system,3D dosimetric mapping that represents a distribution of a radionuclide contamination, a component of modeling for nuclear facility and devices include the decontamination and decommissioning. The research of software architecture about these components was carried out because these component systems that have been independently doesn't describe not only to visual an activities of Decontamination and Decommissioning(D&D) but also to evaluate it. The result was established an architecture that consist of an visualization module which could be visualized an D&D activities and a simulation module which can be evaluated a dismantling schedule and decommissioning cost.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.1
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• pp.41-47
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• 2018

Radioactive substances, especially $^{137}Cs$ discharged in the course of Nuclear Power Plant Accident or maintenance of power plants, cause contamination of the soil. For habitation of residents and reuse of industrial land, it is inevitably necessary to decontaminate the soil. This study examines a soil washing process that has actually been used for washing of radioactive-contaminated soil. The soil washing process uses a washing agent to weaken surface tension of the soil and cesium, separating cesium from the soil. In this study, in order to raise the efficiency of the process, a flocculating agent was added to the washing water to remove fine soil and cesium. The cesium concentrations before and after applying the flocculating agent to cesium solution were measured through ICP-OES. When using 0.1 g of J-AF flocculating agent in the experiment, the maximum Cs removal performance was approximately 88%; the minimum value was 67%. Species combinations between cesium and soil were predicted using Visual MINTEQ Code; the ability to reuse the washing water or not, and the removal rate of the fine soil, determined via measurement of the turbidity after applying the flocculating agent, were determined.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.660-667
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• 2016

Conventional decontamination methods utilize water-based systems, which generate high amounts of secondary wastes. Herein, we describe an environmentally benign decontamination method using liquid and supercritical $CO_2$. The use of $CO_2$ as a solvent affords effective waste reduction by its ability to be recycled, thereby leaving be hind only the contaminants upon its evaporation. In this study, a $CO_2$ solution process was assessed using t-salen(t-butylsalen), DC18C6 (dicyclohexano-18Crown6), 8-HQN(8-hydroxyquinoline), NEt4PFOSA(perfluoro-1-octanesulfonic acid tetra-ethyl ammonium salt), and NEt4PFOA(pentadecafluorooctanoic acid ammonium salt) to extract spiked radioactive contaminants(Nb,Zr,Co,Sr) from an inert sample matrix, namely filter paper. With the static extraction method, Sr was extracted with a maximum extraction rate of 97%, and Nb was extracted with a maximum extraction rate of 75%. Additionally, we were also able to extract Co and Zr with maximum extract ion ratesof 73% and 64%, respectively.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2256-2262
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• 2023

The electrochemical corrosion behaviors of SA106 Grade B (SA106B) carbon steel in H₂SO₄4-N₂H₄ and H₂SO₄-N₂H₄-CuSO₄ solutions at 95 ℃ have been investigated with the addition of commercial corrosion inhibitors (CI#30 and No. 570S), to determine the stability of SA106B in the hydrazine-based reductive metal ion decontamination (HyBRID) process. The potentiodynamic polarization experiment revealed that the corrosion inhibitors were capable of lowering the corrosion rate of SA106B in H₂SO₄-N₂H₄ solution. It was found that the corrosion inhibitors induced formation of fixed surface layer on the carbon steel upon the corrosion. This corrosion inhibition performance was reduced in the presence of CuSO₄ in the solution owing to the chemical reactions between organic compounds in the corrosion inhibitors and CuSO₄. CI#30 showed a better corrosion inhibition effect in the H₂SO₄-N₂H₄-CuSO₄ solution. Although the corrosion inhibitors can provide better stability to SA106B in the HyBRID solution, their application should be carefully considered because it may result in reduced decontamination performance and increased secondary waste generation.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.3
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• pp.335-342
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• 2015

Laboratory facilities for biology are designed as biosafety level 1, biosafety level 2, biosafety level 3, and biosafety level 4. Biosafety level designations are based on a composite of the design features, construction, containment facilities, equipment, practice and operation procedures required for working with agents from the various risk groups. Generally, biosafety level 3 means the facility that is appropriate for the experiments using pathogens which can cause serious diseases by aerosol transmission. The biosafety level assigned for the specific work to be done is driven by professional judgement based on a risk assessment, rather than by automatic assignment according to the particular risk group designation of the pathogenic agents to be used. In this paper, we introduced the biosafety level 3 facility operated in ADD(Agency for defense development). It contains the overview of facility, microbiological experiment, animal experiment, decontamination and waste disposal. Biosafety level 3 laboratory in ADD has served the vital role in the research of biological agents and antidote development.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.2
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• pp.149-157
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• 2005

PFC(Perfluorocarbon) decontamination process is one of best methods to remove hot particulate adhered at inside surface of hot cell and surface of equipment in hot cell. It was necessary to develop a particulate filtration equipment to reuse PFC solution used on PFC decontamination due to its high cost and to minimize the volume of second wastewater. Contamination characteristics of hot particulate were investigated and then a filtration process was presented to remove hot particulate in PFC solution generated through PFC decontamination process. The removal efficiency of PVDF(Poly vinylidene fluoride), PP(Polypropylene), Ceramic(Al$_{2}$O$_{3}$ filter showed more than 95$\%$. The removal efficiency of PVDF filter was a little lower than those of other kiters at same pressure(3psi). A ceramic filter showed a higher removal efficiency with other filters, while a little lower flux rate than other filters. Due to inorganic composition, a ceramic filter was highly stable against radio nuclides in comparison with PVDF and PP membrane, which generate H$_{2}$ gas in e-radioactivity atmosphere. Therefore, the adoption of ceramic filter is estimated to be suitable for the real nitration process.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.1
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• pp.17-23
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• 2008

In this study, plasma processing of metal surface is experimentally investigated to enhance the surface decontamination efficiency and to find out the reaction mechanism. Cobalt, the major contaminant in the nuclear facilities, and three fluorine-containing gases, $CF_4/O_2$, $SF_6/O_2$, and $NF_3$ are chosen for the investigation. Thin metallic disk specimens are prepared and their surface etching reactions with the three plasma gases are examined. Results show that the maximum etching rate of $17.2\;{\mu}m/min.$ is obtained with NF3 gas at $420^{\circ}C$, while with $CF_4/O_2$, $SF_6/O_2$ gas plasmas those of $2.56\;{\mu}m/min.$ and $1.14\;{\mu}m/min.$ are obtained, respectively. Along with etching experiments, constituent elements of the reaction products are identified to be cobalt, oxygen, and fluorine by AES (Auger Electron Spectroscopy) analysis. It turns out that the oxygen atoms are physically adsorbed ones to the surface from the ambient not participation ones during the analysis after reaction, which supports that the surface reaction of cobalt is mainly to be a fluorination reaction.

• Korean Journal of Environmental Agriculture
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• v.18 no.3
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• pp.292-297
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• 1999

This study was performed to estimate the possibility of use of plant materials as catalytic agents fur the decontamination of waste waters contaminated with organic pollutants by using 2,4-dichlorophenol(2,4-DCP) as a model pollutant. Plant materials containing high peroxidase activity were selected as catalysts for the removal of 2,4-DCP. Peroxidase activity, which plant materials were containing, was measured, and the greatest peroxidase activity was observed in shepherd's purse, followed by turnip, sweet potato, Chinese cabbage and white radish. The peroxidase activity in shepherd's purse was four times higher than that of horseradish purchased in U.S.A. Using shepherd' s purse and turnip, it was investigated the effect of various factors on the decontamination of 2,4-DCP through oxidative coupling. The removal of 2,4-DCP was extremely fast, and a maximal removal could be achieved within 3 min for shepherd' s purse and 15min for turnip. The pH range was from 3.0 to 8.0 and the amount of $H_2O_2$ added was 9mM when maximal removal was achieved(over 90%). No increasing removal of 2,4-DCP was observed due to increasing the amount of $H_2O_2$ added (over 9mM). The initial concentration affected the transformation of 2,4-DCP incubated with plant materials. When turnip was used as catalytic agent, it was observed decreasing transformation of 2,4-DCP due to increasing initial concentration.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.849-854
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• 2003

The Korea Atomic Energy Research Institute has developed a teleoperated cleaning robot for use in the radioactive zone of the isolation room of the Irradiated Material Examination Facility where direct human access to the interior is strictly limited. The teleoperated cleaning robot that was designed to completely eliminate human interaction with the hazardous radioactive contaminants has five remotely replaceable submodules - a mobile module for navigation, a cleaning module for dislodging and sucking contaminated waste, a sensing module for obstacle avoidance, a collection module for storing the acquired waste, and a cover module for protecting the collection module. This cleaning robot is capable of cleaning the contaminated floor surface of the isolation room and collecting loose dry spent nuclear fuel debris and other radioactive waste fixed or scattered on the floor surface. The developed cleaning robot is operated either by a manual control or by autonomous control in conjunction with a graphical simulator, by which the human operator can monitor and intervene the robot performing cleanup tasks in the isolation room. In this paper, we present the mechanical and environmental design considerations and development of the teleoperated cleaning robot for radioactive isolation room use. We also demonstrate its mock-up performance test results from the viewpoint of a remote cleanup operation and remote maintenance.